Strap on Porn

So, I normally dont watch women wearing strap ons having sex with men, but I stumbled upon one the other day on Pornhub.

I found it odd that the man's penis never seemed to get hard while the woman pounded his bum. Is that normal? I know when Im getting it in the bum, my vagina gets super wet! I actually sometimes have better orgasms that way.

So I was just curious... maybe I need to watch more strap on porn? ; )